I frankly do not know if it is possible but with a POD starting in the year 1500 and ending in the year 1900, have a significant portion of the Romanian people convert to Islam. Bonus points if it is Wallachia, Moldova, or Transylvania that converts to Islam.
Its actualy not that hard (hell i can covert the entire ottoman balkans including greece and the caucauses if you want).The only reason the balkans didnt completly convert was because the ottomans left the christians to there own devices and the fact that muslims were exterminated in the regions when ever the ottomans lost control of said regions. But i must ask first doesnt it matter how i do it aslong as i dont use ASB's and handwaviums?
Edit: Thought about it hears my ideas.
First some fun facts about the past:
The jizya tax was quite low. Merchants could still do bussiness like muslims some actualy got quite rich. They had there own courst some ran there own regions/villages etc.Social moblity was ofcourse not as high as muslims but it wasnt bad enough that it would hinder there well being greatly. Mehmet had restablished the patriarchy to its former power and glory then as time passed it grew in size and power as the ottomans did. The state did help out churches through the patriarchy. But even though with all of this large swathes did start to convert especialy in the balkans. Too a point that either muslims were a majority of quite a bit of areas or a pularity in others. There was very little areas which they were a minority. But im going to change all that.
Before mehmet took C-town there were mass convertions some were disillusion with there faith or there former master that ruled by that faith or what ever the reasons were. Before mehmet restablished the patriarchy convertion was very high but it all almost completly stoped after it was restablished. So mehmet isnt such a nice guy and eradicates the patriarchy and hangs all of its members (honestly whos going to stop him). After that he raises the jizya tax to a point right before subsistance farming. Takes out all social movement for christians. Makes it very hard for there merchants to do bussiness. Doesnt let them rule thems selves on a local level or any other level for that matter. Doesnt allow christian courst to exsist. Makes it a state policie to put pressure on them to convert. Creates a special fund for islamisation programs. Having schooles hospitals and aid centers connected to the masques to constantly draw them towards them. Creats a fund for langauge programs. Systematicaly eliminating all local written langauges.Replacing it with schools that teach ottoman. Creates and emphasis on converstion and langauge as a state phylosohpy. Makes it extremly difficult for preists and churches to function properly. Effecttively making christion the prime example of second class citizens.Sends goverment officals to every major christian city/province under its control to tell the people that if they convert taxes will go away social mobility will become easy merchants will be able to do bussiness just like every one else.
Through the course of 1400 to 1900 (sorry i had to bring the pod back i need to do that to make it a garante and to change mehmets policies on christians) not only will you have a muslim walachia but a prodominantly muslim balkans greece and caucasus.The point is to get to the 50% mark then its all downhill from there. And that mark will be reached in about a generation or two.
If you just want walachia to be converted then in the battle of 1462 when mehmet goes to walachia with his 60.000 regular and 30,000 iregular troops instead just just invading walachia and taking the capital because vlad refused to meet him on open field (you can say alot about vlad but you cant call him stupid).So Vlad does meet him on open field his
army is desimated and he is killed in battle along with his top commanders. Then just like the otl the capital is taken but this time walachia is over run and the policies i have said above are employed in walachia and large garrison of men are left there to make sure the polices are enforced.
There you have does it suit your needs?